High-temperature creep response of a nickel-based single crystal superalloy with varying initial microstructures

Abstract

This study examines the impact of different initial microstructures on the creep behavior of nickel-based single crystal superalloys. Three alloy samples (A1, A2, A3) with varying γ′ precipitate sizes and matrix channel widths were prepared through different aging treatments and subjected to high-temperature creep tests. Results show that the A2 sample, with moderate γ′ precipitate size and narrow matrix channels, exhibited the best creep resistance, lasting the longest in the steady-state stage. In contrast, A1 and A3 samples transitioned into the tertiary stage earlier due to larger or smaller precipitates and wider channels. Dislocation behavior analysis revealed that narrower matrix channels in A2 hindered dislocation motion, promoting a stable dislocation network and reducing superdislocations during creep. Calculations of critical stress and effective lattice misfit confirmed that A2's microstructure enhanced resistance to dislocation motion and antiphase boundary shearing, contributing to its superior creep performance. Overall, the findings highlight that an optimized γ′ precipitate size and matrix channel width significantly improve creep resistance, providing insights for designing high-performance nickel-based single crystal superalloys.